1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED
2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED
3 
4 // MS compatible compilers support #pragma once
5 
6 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
7 # pragma once
8 #endif
9 
10 //  detail/sp_counted_base_sync.hpp - g++ 4.1+ __sync intrinsics
11 //
12 //  Copyright (c) 2007 Peter Dimov
13 //
14 //  Distributed under the Boost Software License, Version 1.0.
15 //  See accompanying file LICENSE_1_0.txt or copy at
16 //  http://www.boost.org/LICENSE_1_0.txt
17 
18 #include <boost/smart_ptr/detail/sp_typeinfo_.hpp>
19 #include <boost/config.hpp>
20 #include <limits.h>
21 
22 #if defined( __ia64__ ) && defined( __INTEL_COMPILER )
23 # include <ia64intrin.h>
24 #endif
25 
26 #if defined(BOOST_SP_REPORT_IMPLEMENTATION)
27 
28 #include <boost/config/pragma_message.hpp>
29 BOOST_PRAGMA_MESSAGE("Using __sync sp_counted_base")
30 
31 #endif
32 
33 namespace boost
34 {
35 
36 namespace detail
37 {
38 
39 #if INT_MAX >= 2147483647
40 
41 typedef int sp_int32_t;
42 
43 #else
44 
45 typedef long sp_int32_t;
46 
47 #endif
48 
atomic_increment(sp_int32_t * pw)49 inline void atomic_increment( sp_int32_t * pw )
50 {
51     __sync_fetch_and_add( pw, 1 );
52 }
53 
atomic_decrement(sp_int32_t * pw)54 inline sp_int32_t atomic_decrement( sp_int32_t * pw )
55 {
56     return __sync_fetch_and_add( pw, -1 );
57 }
58 
atomic_conditional_increment(sp_int32_t * pw)59 inline sp_int32_t atomic_conditional_increment( sp_int32_t * pw )
60 {
61     // long r = *pw;
62     // if( r != 0 ) ++*pw;
63     // return r;
64 
65     sp_int32_t r = *pw;
66 
67     for( ;; )
68     {
69         if( r == 0 )
70         {
71             return r;
72         }
73 
74         sp_int32_t r2 = __sync_val_compare_and_swap( pw, r, r + 1 );
75 
76         if( r2 == r )
77         {
78             return r;
79         }
80         else
81         {
82             r = r2;
83         }
84     }
85 }
86 
87 class BOOST_SYMBOL_VISIBLE sp_counted_base
88 {
89 private:
90 
91     sp_counted_base( sp_counted_base const & );
92     sp_counted_base & operator= ( sp_counted_base const & );
93 
94     sp_int32_t use_count_;        // #shared
95     sp_int32_t weak_count_;       // #weak + (#shared != 0)
96 
97 public:
98 
sp_counted_base()99     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
100     {
101     }
102 
~sp_counted_base()103     virtual ~sp_counted_base() // nothrow
104     {
105     }
106 
107     // dispose() is called when use_count_ drops to zero, to release
108     // the resources managed by *this.
109 
110     virtual void dispose() = 0; // nothrow
111 
112     // destroy() is called when weak_count_ drops to zero.
113 
destroy()114     virtual void destroy() // nothrow
115     {
116         delete this;
117     }
118 
119     virtual void * get_deleter( sp_typeinfo_ const & ti ) = 0;
120     virtual void * get_local_deleter( sp_typeinfo_ const & ti ) = 0;
121     virtual void * get_untyped_deleter() = 0;
122 
add_ref_copy()123     void add_ref_copy()
124     {
125         atomic_increment( &use_count_ );
126     }
127 
add_ref_lock()128     bool add_ref_lock() // true on success
129     {
130         return atomic_conditional_increment( &use_count_ ) != 0;
131     }
132 
release()133     void release() // nothrow
134     {
135         if( atomic_decrement( &use_count_ ) == 1 )
136         {
137             dispose();
138             weak_release();
139         }
140     }
141 
weak_add_ref()142     void weak_add_ref() // nothrow
143     {
144         atomic_increment( &weak_count_ );
145     }
146 
weak_release()147     void weak_release() // nothrow
148     {
149         if( atomic_decrement( &weak_count_ ) == 1 )
150         {
151             destroy();
152         }
153     }
154 
use_count() const155     long use_count() const // nothrow
156     {
157         return const_cast< sp_int32_t const volatile & >( use_count_ );
158     }
159 };
160 
161 } // namespace detail
162 
163 } // namespace boost
164 
165 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED
166